1. Field of the Invention
The present invention is broadly concerned with an improved, extruded, semi-moist, stable sea urchin feed product which is very efficiently utilized by sea urchins and significantly increases economically important gonadal growth. More particularly, the invention pertains to such extruded feeds which have proper size, texture, specific gravity and water stability properties rendering the feed ideal for the particular feeding habits of sea urchins. The feeds of the invention include protein and carbohydrate, and preferably a humectant (e.g., glycerin, propylene glycol and corn syrup), and have a specific gravity in sea water insuring that the feed will sink.
2. Description of the Prior Art
Sea urchins are marine echinoderms of the class Echinoidea, and have been harvested by man as a food source delicacy for thousands of years. All commercially exploited sea urchins are epibenthic, shallow-water grazers, and typically position themselves atop and slowly feed upon a food source. Sea urchins are harvested according to season for their gonads, which are highly prized in Asian and Mediterranean countries. Indeed, sea urchin gonads are a premium product which command extremely high prices on the world market.
In light of these considerations, it has been suggested in the past that sea urchins be farmed in aquatic cages. Moreover, attempts have been made in the past to provide artificial feeds for sea urchins, so as to replicate or even improve natural sea urchin growth and development. Thus, it has been known to prepare artificial feeds using protein and carbohydrate sources along with organic binders such as agar. These feeds were labor-intensive and expensive to produce, and were thus not commercially viable. From a functional standpoint, many of these prior artificial feeds were also deficient in that they tended to disperse in sea water after a relatively short period of time, and thus did not meet the specialized feeding habits of sea urchins.
There is accordingly a real and unsatisfied need in the art for a improved sea urchin feed product which can be economically produced on a commercial scale and which have the necessary properties of resiliency, specific gravity, nutritional qualities and prolonged self-sustension in sea water allowing the feeds to be used as a natural food substitute for sea urchins in aquatic farming operations.